This invention relates to a high-speed sputtering apparatus using a target of such ferromagnetic substance as Fe, Co, Fe-Ni, Co-Cr, Co-R, Fe.sub.3 O.sub.4, BaO.Fe.sub.2 O.sub.3 and so on.
An apparatus is previously known having an evacuated chamber provided therein with a target of ferromagnetic substance such as Fe or the like as a cathode. It is also known to provide a magnetic field developing means behind the target. This produces a leakage magnetic field on the surface of the target so that the plasma density may be increased.
However, this apparatus is liable to the disadvantage that in order to produce a parallel magnetic field on the surface of the target of such an intensity of about 200 Gauss (which is necessary for a high speed sputtering), it is necessary to make ferromagnetic the target relatively thin. Additionally, it is generally necessary to have the field developing means producing a magnetic field of an intensity more than the magnetic saturation value of the target. This results in the wearing and consumption of the target being accelerated. Consequently, its life is lowered. Namely, for instance, in a case where a barium-ferrite magnet is used as a magnetic field developing means, an Fe target in the form of a plate is used for the ferromagnetic substance target and these are brought into mutually contacting condition, the thickness of the Fe target has to be made less than 1.4 mm in order to obtain a leakage magnetic field of about 200 Gauss on the surface of the target.
When a Cu backing sheet is provided on the back of the Fe target for reinforcing the same, the thickness of the Fe target has to be made less than 0.7 mm. In these cases, the life of use of the target becomes very short, which is undesirable.